JP2020506076A - Method and apparatus for operating a hydraulic expansion clamp device - Google Patents

Abstract

The present invention is a method for operating a hydraulic extension clamping device (3), said hydraulic extension clamping device (3) having a main unit (4), Form a pressure chamber system filled with a hydraulic medium, said pressure chamber system comprising a pressure chamber (15) and a screw hole (8), said pressure chamber (15) being formed by a wall ( 18), the wall (18) defining a clamping surface (19) on the side opposite the pressure chamber (15), the screw holes (8) being introduced from outside into the body device (4). And a connection duct connected to the pressure chamber (15), the crank bolt (9) is screwed into the screw hole (8), and the clamp bolt (9) is screwed into the screw hole (8). Is adjusted axially as a result of As a result, the hydraulic medium is pressed in the direction of the pressure chamber (15) and the wall (18) is elastically deformed to clamp the tool (20) or the workpiece, where in the method: The clamping bolt (9) is rotated by the rotating tool (22) and the torque applied to the hydraulic expansion clamp device (3) is increased, in particular, by the hydraulic expansion crank device (3) being fixed to the holding part (2). Supported.

Description

  The invention relates to a method for operating a hydraulic extension clamping device, in particular a hydraulic extension chuck or a hydraulic extension mandrel, the hydraulic extension crank device having a main body device, the main body device comprising A medium-filled pressure chamber system is formed, the pressure chamber system including a pressure chamber and a threaded hole, the pressure chamber having a wall defining a clamping surface opposite the pressure chamber. The screw hole is drilled from the outside into the main body device, connected to the pressure chamber through a connection passage, and a clamp bolt is screwed into the screw hole, and the clamp bolt is screwed into the screw hole. Upon entry, a hydraulic medium is pressed in the direction of the pressure chamber to clamp the tool or workpiece, and the wall is elastically deformed Axially adjusted, the clamping bolt is rotated using a rotary tool, and the torque provided to the hydraulic expansion clamping device is supported in a stationary holder, in particular by the fixing of the hydraulic expansion clamping device, About the method. Furthermore, the invention relates to a device for operating a hydraulic extension clamping device.

  Hydraulic extension clamping devices can be used for clamping tools as well as for clamping workpieces, basically between two different structural configurations, namely a hydraulic extension chuck and a hydraulic extension mandrel. To be distinguished. The principle function of both structural shapes is the same, that is, the operation of the hydraulic expansion clamp device causes the hydraulic medium, especially the hydraulic oil, to be released within the hydraulic chamber system of the main unit of the hydraulic expansion clamp device and the pressure chamber of the pressure chamber system. In that direction, which results in an elastic expansion of the wall of the pressure chamber defining the clamping surface. The expansion of the wall first compensates for the chuck gap between the wall and the tool or workpiece to be clamped, and then presses the wall against the tool or workpiece to be clamped, This creates a frictional connection between the hydraulic extension clamping device and the tool or workpiece. The only difference between the two configurations lies in the clamping profile. That is, the hydraulic extension mandrel clamps the workpiece through a hole in the workpiece, while the hydraulic extension chuck clamps the tool shank through the central tool receiving portion of the hydraulic extension chuck.

  The operation of the hydraulic expansion clamp device can be performed in various ways. In order to generate sufficient hydraulic pressure for the clamping in the hydraulic chamber system of the hydraulic extension clamping device, it is possible on the one hand to operate with a clamping cylinder and a pressing or pulling rod. On the other hand, it is possible to carry out a direct load using hydraulic equipment. In addition, the hydraulic extension clamping device can be operated by rotating a clamping bolt with a rotating tool. In this case, it is known to support the torque applied to the hydraulic expansion clamp device by fixing the hydraulic expansion clamp device particularly to a stationary holding portion. The present invention relates to the last-mentioned mode of operation using a clamp bolt.

  If the hydraulic expansion clamping device is a hydraulic expansion chuck, the above-mentioned main body device of the hydraulic expansion chuck includes a main body, and the main body includes a mechanical interface in a rear end region thereof, Via the mechanical interface, the hydraulic expansion chuck can be fixed to a corresponding tool holder receptacle on the tool machine. On the opposite side of the body, there is formed a clamping area having a central tool housing opening towards the front end face of the body, into which the tool shank to be clamped is inserted. It is possible. In some hydraulic expansion chucks, the body also includes an expansion bushing, the expansion bushing forming a tool housing, which surrounds the expansion bush and applies a load with a hydraulic medium. The pressure chamber is fitted into the body while forming a pressure chamber capable of being operated, and opens toward the front end face of the body.

  Hydraulic extension clamping devices are subject to wear and abrasion during their use in the industry, and as a result, to ensure process safety and to avoid production losses due to accidental detachment of tools or workpieces, It is important to periodically check the condition and performance of the type expansion clamp device. By measuring the clamping force, it is possible to calculate the performance that still exists and the wear that has occurred.

  In some known methods and devices for operating a hydraulic expansion clamp device, the clamping state or performance of the hydraulic expansion clamp device is determined during the insertion of the clamping bolts and thus during the operation of the hydraulic expansion clamp device. Can not. The measurement of the clamping force for determining the clamping state of the hydraulic extension clamping device has heretofore always had to be performed separately and with additional measuring devices and measuring structures. For measuring the clamping force, in a known manner, a torque wrench, a plug gauge or a special clamping force tester for the hydraulic extension clamping device can be used. A disadvantage of plug gauges or clamping force testers in particular is that this makes it impossible for the hydraulic extension clamping device to determine the performance of the tool or workpiece clamp during its operation and the measurement must be performed in a separate step. There is to be. This is both tedious and time consuming.

  Against this background, the problem underlying the present invention is that a hydraulic extension clamping device of the type mentioned at the beginning can be used to determine the actual clamping state of the hydraulic extension clamping device during the insertion of the clamping bolt. Is to provide a method and apparatus for operating the. In addition, a corresponding device for operating the hydraulic expansion clamping device is provided.

The object is, according to the invention, a method for operating a hydraulic extension clamping device of the type mentioned at the outset, comprising the following steps:
a) measuring the hydraulic medium pressure-indicated value with a measuring device at a pre-set uniform measuring interval and / or continuously during the rotation of the clamp bolt;
b) identifying the clamped state of the hydraulic expansion clamp device by evaluating the measured hydraulic medium pressure-display value using the evaluation and control device;
c) signaling the determined clamping state of the hydraulic extension clamping device to a user using a signaling device.

  Thus, the underlying consideration of the invention is that the actual value of the clamping force of the hydraulic extension clamping device should be such that the value of the hydraulic medium pressure-the indicated value during the clamping of the clamping bolt and thus during the clamping of the hydraulic extension clamping device. It is to determine the clamping state of the hydraulic extension clamping device by measuring indirectly via the measurement and evaluating the measured value. With an appropriate evaluation of the detected measurements, it is possible to deduce the performance and / or wear and / or possible failure of the hydraulic extension clamping device and thus to derive the actual clamping state of the hydraulic extension clamping device Becomes The clamping state thus determined of the entire system consisting of a hydraulic extension clamping device, a clamped tool or a workpiece is directly communicated to the user in a comfortable and easily understandable manner. Therefore, when the minimum clamping force or the target clamping force of the hydraulic extension clamping device is reached, the user does not need to access the whole system from the outside and check it by himself, but is signaled, for example, to the user.

  According to one aspect of the invention, the rotating tool is automatically oriented relative to the hydraulic extension clamping device and is automatically engaged with the clamping bolt. Thereby, it is possible to secure the engagement performance kept constant.

  After the engagement performed, the clamping bolt can be automatically rotated using a screwing device, in particular an electric screwing device, on which the rotating tool is held. For example, the electric screw tightening device is a battery-type screw tightening device, and the rotating tool is a hexagonal bit rotatably held by the power storage type screw tightening device. The electric screwing device has the advantage, inter alia, that it is possible to achieve a constant screw-in speed of the clamping bolt. Alternatively, the clamp bolt can be rotated manually using a rotating tool, in particular a screwdriver.

  In step a), during the screwing of the clamping bolt, the value of the hydraulic medium pressure-the value of the hydraulic medium pressure as an indicated value can be measured in the pressure chamber system and / or at the clamping bolt via a pressure sensor. It is. Thus, in this case, a direct measurement of the pressure takes place. In some hydraulic extension clamping devices, a cylindrical bore in the pressure chamber system is axially adjacent to a threaded hole in the hydraulic chamber system, and a clamp piston is located in the cylindrical bore, and the clamp piston is attached to a clamp bolt. It is in contact with or connected to the clamp bolt, so that the axial adjustment of the clamp bolt when screwed into the threaded bore causes the axial adjustment of the clamp piston. The advantage of the clamp piston is that the clamp bolt can be completely screwed out when the clamp is released, without the negative effect of the screw hole. This is because the clamping piston is always in the corresponding cylindrical bore and therefore the pressure chamber system remains sealed. In the case of a hydraulic extension clamping device having a clamp piston, in step a), during the screwing of the clamp bolt, the value of the hydraulic medium pressure at the clamp piston instead of the clamp bolt—the value of the hydraulic medium pressure as display value , Can be measured via a pressure sensor. Due to the direct measurement of the pressure of the hydraulic medium, the possible conversion of the hydraulic medium pressure to the indicated value into the pressure value is omitted.

  Additionally or alternatively, in step a), during the screwing of the clamping bolt, a value of the amount complementary to the pressure of the hydraulic medium is measured as hydraulic medium pressure-indicated value. It is possible. In this case, the pressure of the hydraulic medium is not measured directly, but indirectly via other quantities. This eliminates the need for making changes in the pressure chamber system, such as, for example, mounting a pressure sensor.

  Similarly, as a complement to the pressure of the hydraulic medium, the deformation, in particular the expansion and / or the extension, of the body device can be measured with a strain gauge as the hydraulic medium pressure-indicated value. . Such a strain gauge can be provided, for example, on the outer surface of the main body device without much trouble.

Preferably, the torque at the clamp bolt as an amount complementary to the pressure of the hydraulic medium is measured as hydraulic medium pressure-indicated value. At this time, the measurement of the torque of the clamp bolt can be performed using the strain gauge provided on the torsion shaft through the measurement of the torsion of the torsion shaft. When the clamp bolt is rotated using the electric screw tightening device holding the rotating tool, the measurement of the torque at the clamp bolt determines the motor current of the motor of the electric screw tightening device at a constant motor rotation speed. It can also be done via measurement. That is, the motor current I follows a relational expression M = k _M × (I−I ₀ ) in proportion to the torque M, where I ₀ is an idling current due to friction, and k _M is a voltage constant. through _{k M = 3 / π × k} E in k _E is a torque constant to be associated. Measuring the torque of the clamp bolt via the motor current is extremely simple. This is because the measurement does not require a change in the hydraulic expansion clamping device to be clamped.

  During the screwing of the clamp bolt, in addition to the hydraulic medium pressure-display value measured in step a), a further clamp bolt stroke-display value, in particular initiated by the occurrence of a predefined trigger event, Or it may be advantageous to start by measuring a pre-defined trigger value and to perform at predetermined equal measuring intervals and / or continuously. At this time, the measurement interval between two directly measured hydraulic medium pressures and the indicated value is preferably the measurement interval between two directly measured clamp bolt strokes and the indicated value, particularly the clamp interval. This corresponds to a preset stroke step, angle step, or time step when the screwing speed of the bolt is constant. The trigger event is a contact of the clamping surface with a tool or workpiece to be clamped and / or an abutment of the clamping bolt at a stopper which limits the axial adjustment of the clamping bolt, and / or the trigger value is a predetermined value. The value of the hydraulic medium pressure characteristic of the hydraulic expansion clamping device used in the trigger event of the present invention or a value of the amount complementary thereto. The trigger value may be a threshold value of the hydraulic medium pressure or an amount complementary thereto, preferably 20% (for hard bolts) and 80% of the pressure value or the amount complementary thereto. (In the case of a flexible bolt), the trigger value terminates the screwing of the clamp bolt, and therefore, between 20% and 80% of the off-torque value when the clamp bolt comes into contact. It is in. The measured clamp bolt stroke-indicated value can be used to obtain confirmation as to whether the defined clamping state is correct based on the measured hydraulic medium pressure-indicated value.

  The value of the axial stroke position of the clamp bolt in the screw hole can be measured as clamp bolt stroke-display value. In this case, the clamp bolt stroke is measured directly. Therefore, a possible conversion of the clamp bolt stroke minus the indicated value into a clamp bolt stroke is omitted.

  Additionally or alternatively, a value of the amount complementary to the axial stroke position of the clamp bolt in the screw hole can be measured as clamp bolt stroke-indicated value. In this case, the clamp bolt stroke is measured indirectly via another quantity measurement. Advantageously, the angle of rotation of the clamp bolt as an amount complementary to the axial stroke position of the clamp bolt in the screw hole is preferably determined using an encoder and / or using a Hall sensor. It is measured directly on the bolt or on a rotating tool or on a screw-fastening device in which the rotating tool is held. In the case of an electric screw tightening device having an electric motor, a Hall sensor can be used to detect the rotor position of the motor. Brushless DC motors (BLDC) are particularly advantageous. That is, in such a motor, a position signal is required for electronic rectification, and therefore, in a BLDC motor, the position of the rotor is known. The measurement of the angle of rotation via an encoder or a Hall sensor at the clamping bolt is particularly simple. This is because the measurement does not require a change in the hydraulic expansion clamping device to be clamped. Thus, such a rotation angle measurement contributes to being able to identify the clamping state for different hydraulic expansion clamping devices during operation. With the measured rotation angle and the known pitch of the screw of the clamp bolt, it is possible to calculate the returned stroke of the clamp bolt and possibly the clamp piston. If the rotation speed of the clamp bolt is constant, the rotation time can be measured as a complementary amount to the axial stroke position of the clamp bolt.

In order to determine the clamping state of the hydraulic expansion clamping device in step b) by evaluation of the measured hydraulic medium pressure-display value, it is advantageous in step b) to carry out the following sub-steps:
b1) Check whether the hydraulic medium pressure-indicated value measured when the clamp bolt is screwed is within a predefined range for the hydraulic medium pressure-indicated value characteristic of the type of hydraulic extension chuck used. The process of checking,
b2) If the check in step b1) yields a positive result, the step of estimating the clamping state of the hydraulic extension clamping device assigned to the characteristic hydraulic medium pressure-display value is performed.

  Preferably, the characteristic hydraulic medium pressure-display value is a characteristic hydraulic medium pressure-display value at the time of contact of the clamping surface with the tool or workpiece to be clamped, and the assigned clamping state is The contact between the clamping surface and the tool or the workpiece and / or the characteristic hydraulic medium-reading value is a characteristic when the clamping bolt abuts against a stopper which limits the axial adjustment of the clamping bolt. Hydraulic medium pressure-indicated value, the assigned clamping state being the attainment of a predefined target clamping force of the used hydraulic extension clamping device. The predefined target clamping force can lead to small deviations in a trouble-free hydraulic expansion clamping device, for example, due to manufacturing tolerances of the clamped tool or workpiece. However, as the number of actuations of the hydraulic expansion clamping device increases, its wear, and consequently the maximally achievable clamping force, increases so that it will no longer reach the preset target clamping force anymore.

Alternatively or additionally, in order to determine the clamping state of the hydraulic extension clamping device by evaluating the measured hydraulic medium pressure-display value, in step b) the following sub-steps:
b3) a step of calculating the gradient of the hydraulic medium pressure-display value measured at a predetermined uniform measurement interval during the insertion of the clamp bolt in the step a), wherein the gradients are measured continuously with each other. Forming a gradient based on the difference between the two hydraulic medium pressure-display values or its value as the dividend and the measurement interval between the two hydraulic medium pressure-display values considered as the divisor;
b4) identifying a gradient change between each two computed gradients;
b5) checking whether the identified gradient change is outside a predefined range, and thus there is an obvious gradient change;
b6) identifying possible causes for apparent gradient changes, especially by taking into account further measurements and / or target values;
b7) estimating the clamp state of the hydraulic expansion clamp device based on the identified cause.

  The calculation of the gradient and the consideration of the gradient change offer the advantage over the pure consideration of the absolute value that the characteristic pressure jump can be ascertained for the hydraulic expansion clamping device used.

  Prior to calculating the gradient in step b3), the hydraulic medium pressure-indicated value measured in step a) is converted to a scale having a multiple of the measuring interval between two directly measured hydraulic medium pressure-indicated values. The resulting measurement curve can in particular be smoothed by the calculation of a moving average and / or at least one particularly linear curve fit in said measurement curve is performed. It is possible to This makes it possible to confirm a clear gradient change.

  Preferably, a gradient change between the two gradients calculated from the three hydraulic medium pressures-display values measured directly directly in step b3) is determined in step b4). Since both gradients used in the calculation of the gradient change are directly continuous in the measurement time series, it is important to note that in the case of an apparent gradient change that has been identified, the gradient change occurs in the average of the three measurements considered. It is possible to guess unambiguously. The gradient change can be identified in step b4) by subtracting or dividing each of the two gradients calculated in step b3) from each other. If the two computed slopes are divided for the determination of a gradient change, the predefined range considered during the check in step b5) may be the predefined minimum multiple of the gradient. Then, a clear gradient change is confirmed when the larger gradient of the two gradients considered is a multiple of the smaller gradient and the corresponding multiple exceeds a predefined minimum multiple.

  If, during the check in step b5), no apparent change in slope is observed until the stop limiting the axial adjustment of the clamping bolt is reached, the tool or workpiece to be clamped is not present or the shaft is too small. It can be inferred that a tool having a clamping or a workpiece with an incompatible clamping diameter is used. However, once a clear gradient change has been identified, the cause can be identified in step b6) by taking into account further measured and / or target values. As will be described in more detail below, it is possible, for example, to take into account a clamp bolt stroke-display value, a target value for the clamp bolt stroke-display value and / or a target value for the hydraulic medium pressure-display value. However, the cause of the apparent gradient change can be identified without taking into account further measurements and / or target values. That is, at least two distinct gradient changes when the clamp bolt is screwed in, a first gradient change upon contact of the clamping surface with the tool or workpiece to be clamped, and an axial adjustment of the clamp bolt. It is known that it is necessary to set a second gradient change when the clamp bolt abuts on the stopper to be restricted. Disregarding the fear that the identified gradient change may also be due to a failure of the hydraulic expansion clamping device, for example, the clamping of a clamping bolt, the apparent gradient change identified is temporarily the first or second. Can be inferred based solely on whether there is an apparent gradient change in the hydraulic expansion clamp device described above.

  As described above, during the screwing of the clamp bolt, in addition to the hydraulic medium pressure-display value measured in step a), the clamp bolt stroke-display value can be measured at a preset uniform measuring interval. The measuring interval between the two directly measured hydraulic medium pressures-reading values corresponds to the measuring interval between two directly measured clamp bolt strokes-reading values. In this case, preferably, in step b6), the measured clamp bolt stroke-indicator value at the time of the apparent gradient change is a known clamp bolt stroke-indicator characteristic for the type of hydraulic extension clamping device used. By comparing with at least one target value for the value, the cause for the presence of a clear gradient change is determined. Thus, the clamp bolt stroke-display value comparison provides for the actual identification of the exact cause for the apparent gradient change identified. Clamp bolt stroke-The target value for the indicated value is the abutment of the clamp bolt on contact of the clamp surface with the tool or workpiece to be clamped and / or on a stopper which limits the axial displacement of the clamp bolt. Time clamp bolt stroke-may be a displayed value.

  Advantageously, when the clamping bolt is screwed in, the torque at the clamping bolt as a complementary quantity to the pressure of the hydraulic medium is measured as described above as hydraulic medium pressure-display value, and in step b6): The measured clamp bolt stroke-display value is out of the range of the target value based on a comparison between the clamp bolt stroke-display value measured at the time of the apparent gradient change and the target value of the clamp bolt stroke-display value. The failure of the hydraulic expansion clamp device is identified as the cause for the presence of a clear gradient change when it occurs, therefore, that it is much smaller than the target value. A failure of the hydraulic extension clamping device can be identified as catching the clamping bolt in the screw hole. Clamping of the clamp bolt can occur because the external thread of the clamp bolt does not meet the required surface conditions or the clamp bolt no longer has sufficient lubrication. However, in the last-mentioned situation, it is also possible to identify a tool with an excessive shaft diameter or a workpiece with an under-hole as a cause for the presence of obvious gradient changes instead of a failure of the hydraulic expansion clamping device. It is possible. That is, for example, if a tool with an excessively large shaft diameter is in the hydraulic expansion chuck, the shaft will come into contact with the clamping surface earlier than expected, and already a noticeable gradient change will occur in a shorter clamping bolt stroke.

  Alternatively or in addition to the above-mentioned consideration of the bolt stroke-display value at the time of determining the cause of the apparent gradient change, in step b6) the hydraulic medium pressure measured at the apparent gradient change-display The value is compared with at least one target value for the known hydraulic medium pressure-display value, characteristic of the type of hydraulic expansion clamping device used, to determine the presence of a gradient change evident. The cause can be identified. In this case, preferably, the target value for the hydraulic medium pressure-display value is a stopper which limits the axial adjustment of the clamping bolt when the clamping surface comes into contact with the tool or workpiece to be clamped. Is the hydraulic medium pressure at the time of contact of the clamp bolt in-.

  Suitably, in step b6) of the method according to the invention, contact of the clamping surface with the tool or workpiece to be clamped is presumed to be the cause of the presence of a clear gradient change, and in step b7) Based on the specified cause, the reaching of the minimum clamping force is estimated as the clamping state.

Preferably, the method according to the invention comprises the following further steps:
-In step b6) the contact of the clamp bolt with a stopper limiting the axial adjustment of the clamp bolt is presumed to be the cause of the presence of a distinct gradient change;
The hydraulic expansion pressure device used for the hydraulic medium pressure-display value at the time of the apparent gradient change, the hydraulic medium pressure at the stop of the clamp bolt at the stopper which limits the axial adjustment of the clamp bolt; Comparing to a known target characteristic of the type of
-Both hydraulic medium pressures to be compared with each other-the step of confirming that the indicated values match within a predefined range;
A step of estimating the arrival of the target clamping force in the step b7) as a clamped state based on the prior confirmation.

  The above comparison of hydraulic medium pressure-display value makes it possible to check whether sufficient clamping force is provided. This cannot be inferred solely on the basis of the fact that the clamp bolt has reached the stopper. The reason for this is that the maximum clamping force of the hydraulic extension clamping device obviously decreases as the number of operations increases.

  Advantageously, during the evaluation of the measured hydraulic medium pressure-indicated value in step b), if it is ascertained that the predefined off-condition has been fulfilled, the clamping bolt is screwed in with a rotary tool. Can be terminated. At this time, the insertion of the clamp bolt in the electric screw tightening device can be terminated by turning off the electric screw tightening device. A mechanical disengagement clutch is also conceivable. The predefined off-condition is the known hydraulic medium pressure-indicated value characteristic of the type of hydraulic extension clamping device used when the clamping bolt abuts against a stopper which limits the axial adjustment of the clamping bolt. For example, it may be a predetermined maximum torque for a hydraulic expansion clamping device that needs to be achieved within a predefined range. If the upper threshold value for the torque difference is greater than, for example, 500 mNm or the corresponding torque gradient value is greater than, for example, 15000 mNm / °, the screw-in is determined when measuring the torque as a complement to the pressure of the hydraulic medium. For example, it is possible to end. Timely termination of the operation prevents damage to the hydraulic extension clamping device.

  Preferably, the clamping state specified in step c) is signaled to the user by means of an indication via an optical, acoustic or vibration signal.

The object of the invention is to provide, according to the invention, a hydraulic extension clamping device, in particular a device for operating a hydraulic extension chuck or a hydraulic extension mandrel, comprising a main unit, which is filled with a hydraulic medium. A pressure chamber system is formed, the pressure chamber system including a pressure chamber and a screw hole, the pressure chamber having a wall defining a clamping surface opposite the pressure chamber, and a screw chamber. The hole is drilled from the outside into the main unit, connected to the pressure chamber through a connection passage, a screw bolt is screwed into the screw hole, and the clamp bolt is screwed into the screw hole, so that a tool or a workpiece is formed. The solution is solved by clamping the piece by pressing a hydraulic medium in the direction of the pressure chamber and adjusting it axially so that the wall is elastically deformed. . At this time, the device according to the present invention
A holding device, in particular an immovable holding portion, configured to support the torque exerted on the hydraulic extension clamping device during rotation of the clamping bolt;
A measuring device configured to measure the hydraulic medium pressure-indicated value at pre-defined uniform measuring intervals during rotation of the clamping bolt and / or continuously;
-Hydraulic medium pressure measured by said measuring device-an evaluation and control device formed to evaluate the indicated value and to specify the clamping state of the hydraulic extension clamping device;
A signaling device configured to signal to the user the clamping state of the hydraulic extension clamping device specified by the evaluation and control device.

  The holding device can be a vise or a grip. However, the holding device may be a steep taper-clamp having a support arm or hollow shaft taper (HSK) or collet chuck set formed to secure the hydraulic expansion clamp device. The holding device can have a support surface corresponding to the support surface in the hydraulic expansion clamp device.

  Preferably, the device according to the present invention comprises a rotating tool configured to rotate the clamping bolt. The rotary tool may be, for example, a bit, especially a hex bit or wrench, especially a hex torque wrench.

  Advantageously, the device according to the invention comprises a screwing device, in particular an electric screwing device, which holds the rotating tool for automatically rotating the clamping bolt.

  The device according to the invention comprises an adjusting device having a holder for the rotating tool, for automatically orienting the rotating tool relative to the hydraulic extension clamping device and for automatically engaging the clamping bolt or A screw fastening device holding the rotating tool can be provided. At this time, the adjusting device has a one-axis, two-axis, three-axis or five-axis movement mechanism, and may be a combination of an industrial robot such as a folding arm robot or a linear module and a rotation axis. Alternatively, in a fixedly integrated system, it is possible to completely omit the movement mechanism and to realize the transmission of torque from the rotary tool to the clamp bolt via a flexible shaft.

  Preferably, the measuring device includes a pressure sensor. The pressure sensor is configured to measure the pressure of the hydraulic medium during the screwing of the clamp bolt as a hydraulic medium pressure-indicated value in the pressure chamber system and / or at the clamp bolt. In some hydraulic extension clamping devices, a cylindrical bore in the pressure chamber system is axially adjacent to a threaded hole in the hydraulic chamber system, and a clamp piston is located in the cylindrical bore, and the clamp piston is attached to a clamp bolt. It is in contact with or connected to the clamp bolt, so that the axial adjustment of the clamp bolt when screwed into the threaded bore causes the axial adjustment of the clamp piston. In this case, the pressure sensor can be configured to measure the pressure of the hydraulic medium at the clamp piston instead of the clamp bolt.

  Advantageously, the measuring device is configured to measure a value complementary to the pressure of the hydraulic medium as the hydraulic medium pressure-indicated value during the insertion of the clamping bolt. To this end, the measuring device can include a strain gauge in the main unit. The strain gauge is configured to measure the deformation, in particular the expansion and / or the extension, of the body as a quantity complementary to the pressure of the hydraulic medium, as a hydraulic medium pressure-display value. Alternatively or additionally, the measuring device is configured such that the torque as a complementary quantity to the pressure of the hydraulic medium is measured as the hydraulic medium pressure during the screwing of the clamping bolt minus the indicated value. It is possible to be. To this end, the measuring device can include a strain gauge provided on the torsion shaft, which measures the torsion of the torsion shaft and, based on this, the torque at the clamping bolt, and here again based on this. It is formed so that the pressure of the hydraulic medium can be calculated. If the device according to the invention comprises an electric screwdriver with a motor and the electric screwdriver holds a rotating tool, the measuring device comprises an ammeter. The current measuring device measures the motor current of the electric screw tightening device at a constant motor rotation speed, and based on this, calculates the torque at the clamp bolt and the pressure of the hydraulic medium again based on this. It is formed to obtain.

  According to one aspect of the invention, the measuring device starts the clamp bolt stroke-indicated value, in particular when a predefined trigger event has occurred or when a predefined trigger value has been measured, The measuring interval between two hydraulic medium pressures-indicated values, which are measured directly and continuously, at a predetermined uniform measuring interval and / or continuously during the screwing of Corresponds, in particular, to the measuring interval between two clamp bolt strokes which are measured directly directly and the indicated value. The trigger event is then the contact of the clamping surface with the tool or workpiece to be clamped and / or the abutment of the clamping bolt on a stopper which limits the axial adjustment of the clamping bolt, and / or the trigger value May be a hydraulic medium pressure value or a complementary amount value characteristic of the hydraulic expansion clamp device used in a given trigger event.

  The measuring device measures the value of the axial stroke position of the clamp bolt in the screw hole and / or the value of the amount complementary to the axial stroke position of the clamp bolt as the clamp bolt stroke-indicated value. It can be formed as follows.

  Preferably, the measuring device determines the angle of rotation of the clamp bolt as a complementary quantity to the axial stroke position of the clamp bolt in the screw hole, directly at the clamp bolt, or at a rotary tool, or at a rotary tool. The tool is configured to measure in a held screw tightening device. The measuring device can include an encoder and / or a Hall sensor to measure the angle of rotation of the clamp bolt. The evaluation and control device can be configured to calculate the returned stroke of the clamp bolt using the measured rotation angle and the known pitch of the screw of the clamp bolt.

  Advantageously, the evaluation and control device provides that the hydraulic medium pressure-indicated value measured when the clamping bolt is screwed in is pre-defined for the hydraulic medium pressure-indicated value characteristic of the type of hydraulic expansion chuck used. It is configured to check if it is within the range and to infer the clamping state of the hydraulic extension clamping device assigned to the characteristic hydraulic medium pressure-indicated value when the check has a positive result. I have. At this time, the characteristic hydraulic medium pressure-display value is a characteristic hydraulic medium pressure-display value at the time of contact of the clamping surface with the tool or workpiece to be clamped, and the assigned clamping state is The contact between the clamping surface and the tool or the workpiece and / or the characteristic hydraulic medium-the indicated value is a characteristic value when the clamping bolt abuts against a stopper which limits the axial adjustment of the clamping bolt. Hydraulic medium pressure-indicated value, the assigned clamping state may be the attainment of a predefined target clamping force of the hydraulic extension clamping device used.

The evaluation and control device
-The hydraulic medium pressure measured by the measuring device at predetermined equal measuring intervals during the insertion of the clamp bolts-the gradient of the indicated value is calculated and each of the two hydraulic medium pressures measured successively to one another-display So that a gradient is formed based on the difference between the values or the value of the hydraulic medium pressure considered as the divisor and the hydraulic medium pressure considered as the divisor-the measurement interval between the indicated values.
-To specify the gradient change between each two calculated gradients,
To check whether said specified gradient change is outside a predefined range, and thus whether there is an obvious gradient change,
-To identify possible causes for apparent gradient changes, in particular by taking into account further measured and / or desired values; and-based on the identified causes, to clamp the hydraulic extension clamping device. It can also be formed to infer the state.

  Advantageously, the evaluation and control device compares the hydraulic medium pressure-display value measured by the measuring device with the measuring interval between two directly measured hydraulic medium pressure-display values before calculating the gradient. Plotting against a scale having multiples, the resulting measurement curve is smoothed, in particular by the calculation of a moving average, and / or at least one particularly linearly performing a curve fitting on the measurement curve. Is formed.

  Preferably, the evaluation and control device is configured to determine the gradient change between the two gradients calculated based on the three directly measured hydraulic medium pressure-display values.

  The evaluation and control device can be formed to determine the gradient change by subtracting or dividing the two computed gradients from each other.

  As mentioned above, the measuring device can be configured to measure the clamp bolt stroke-display value in addition to the hydraulic medium pressure-display value at a pre-set uniform measuring interval during the insertion of the clamp bolt. The measuring interval between two directly measured hydraulic medium pressures-indicated values corresponds to the measuring interval between two directly measured clamp bolt strokes-indicated values. In this case, preferably, the evaluation and control device determines the clamp bolt stroke measured at the time of the apparent gradient change by a known clamp bolt stroke characteristic of the type of hydraulic extension clamping device used. The comparison is made with at least one target value for the indicated value so that the cause for the presence of the apparent gradient change is determined. The target value for the clamp bolt stroke-display value is then the clamp bolt at the time of contact of the clamp surface with the tool or workpiece to be clamped and / or at the stopper which limits the axial displacement of the clamp bolt. May be a clamp bolt stroke at the time of abutment-display value.

  Advantageously, the measuring device is configured such that, when the clamping bolt is screwed in, the torque at the clamping bolt as a complement to the pressure of the hydraulic medium is measured as hydraulic medium pressure-indicated value. The evaluation / control device compares the clamp bolt stroke-display value measured at the time of a clear gradient change with the target value of the clamp bolt stroke-display value, and based on the comparison, the measured clamp bolt stroke-display value. When the value occurs outside the range for the target value, and therefore much less than the target value, a failure of the hydraulic expansion clamp device is identified as the cause for the presence of an apparent gradient change. Have been. At this time, the failure of the hydraulic expansion clamp device may be the capture of the clamp bolt in the screw hole.

  Preferably, the evaluation and control device determines the hydraulic medium pressure-indicator value measured at the time of the apparent gradient change with a known hydraulic medium pressure-indicator value characteristic of the type of hydraulic expansion clamping device used. Is compared to at least one target value to determine the cause of the presence of the apparent gradient change. At this time, the target value for the hydraulic medium pressure-display value is the clamp bolt at the time of contact of the clamp surface with the tool or workpiece to be clamped and / or at the stopper which limits the axial adjustment of the clamp bolt. Hydraulic pressure at the time of abutment-display value.

  The evaluation and control device estimates contact of the clamping surface with the tool or workpiece to be clamped as a cause of the presence of a clear gradient change, and based on the cause, estimates the reaching of the minimum clamping force as the clamping state. It can be formed to:

The evaluation and control device includes:
Guessing the contact of the clamp bolt with a stopper that limits the axial adjustment of the clamp bolt as the cause of the apparent gradient change;
The hydraulic medium pressure measured by the measuring device at the time of the apparent gradient change is used to indicate the hydraulic medium pressure when the clamp bolt abuts on the stopper which limits the axial adjustment of the clamp bolt; Compared with the known target value characteristic of the type of hydraulic expansion clamp device,
-Both hydraulic medium pressures to be compared with each other-check that the indicated values match within a predefined range,
It can also be configured to estimate the reaching of the target clamping force as a clamping state based on the confirmation.

  Preferably, the evaluation / control device is configured to check whether a predetermined OFF condition is satisfied, and to terminate the screwing of the clamp bolt if the result of the check is positive. At this time, the predetermined OFF condition is a known hydraulic medium pressure-display characteristic for the type of the hydraulic extension clamping device used when the clamp bolt at the stopper restricts the axial adjustment of the clamp bolt. It can be a value.

  Suitably, the signaling device comprises a lamp, a speaker, a display and / or a vibration device.

  For other advantages and other possible forms of the device according to the invention, reference is made to the description relating to the method according to the invention in order to avoid repetition.

  Other features and advantages of the present invention are set forth in the following description of five embodiments of a device for operating a hydraulic expansion clamping device according to the invention and a hydraulic expansion chuck operated by a method according to the invention. This will be clearly described with reference to the drawings of FIG.

1 is a schematic perspective view of a device according to the invention for operating a hydraulic expansion clamping device according to a first embodiment of the invention; FIG. 4 is a schematic perspective view of a device according to the invention for operating a hydraulic expansion clamping device according to a second embodiment of the invention. FIG. 7 is a schematic perspective view of a device according to the invention for operating a hydraulic expansion clamping device according to a third embodiment of the invention. FIG. 9 is a schematic perspective view of a device according to the invention for operating a hydraulic expansion clamping device according to a fourth embodiment of the invention. FIG. 11 is a schematic perspective view of a device according to the present invention for operating a hydraulic expansion clamping device according to a fifth embodiment of the present invention. 1 is a schematic perspective view of a hydraulic expansion chuck operable by the method according to the invention. FIG. 7 is a sectional view along a longitudinal center plane of the hydraulic expansion chuck according to FIG. 6. FIG. 8 is a cross-sectional view taken along section line VIII-VIII in FIG. 7. FIG. 4 shows the torque curve depending on the rotation angle for a hydraulic expansion chuck with or without a tool in the central tool housing.

  1 to 5 show schematic perspective views of a device according to the invention for the operation of a hydraulic expansion clamping device (1) according to five different embodiments of the invention. The device (1) according to the invention comprises in all five embodiments a holding device (2), in which a hydraulic expansion clamping device (3) is fixed in the form of a hydraulic expansion chuck. I have.

  The hydraulic expansion chuck (3) is shown in detail in FIGS. The hydraulic expansion chuck includes a main body device (4), and the main body device (4) has a main body (5). The body is provided with a machine interface (6) in its rear end region. The machine interface (6) is for fixing the hydraulic expansion chuck (3) to the holding device (2), and has a clamping area (7) on the opposite side of the machine interface (6). In the central area of the main body (5) between the rear end area and the clamp area (7), a screw hole (8) is drilled from the outside into the main body (5). Is screwed with a clamp bolt (9). The screw hole (8) is provided at its inner end with a stopper (10). This stopper (10) limits the axial displacement of the clamp bolt (9) in the screw hole (8). A cylindrical hole (11) is adjacent to the screw hole (8) in the axial direction. The cylindrical hole is connected to a clamp bolt (9) on one side and a clamp piston (12) on the opposite side. The clamping piston (12) is arranged and is connected to a sealing element (13). The main body device (4) further includes an expansion bush (14) in addition to the main body (5). The extension bush (14) forms a tool housing (17). The tool housing (17) is metallically coupled to the main body (5) in the clamping area (7) of the main body (5) while forming a pressure chamber (15) surrounding the expansion bush (14). And is open toward the front end face (16) of the main body. Thus, the pressure chamber (15) comprises a wall (18), which defines a clamping surface (19) on the side opposite the pressure chamber (15). In addition, the pressure chamber (15) is connected to the cylindrical hole (11) and the screw hole (8) via the connection passage, forming a pressure chamber system filled with hydraulic medium, and It is possible to apply a load. As can be seen in FIGS. 1 to 5, a tool (20) is inserted in the tool housing (17).

  In addition, the device (1) according to the invention comprises, in all five embodiments, an electric screwing device (21) with a motor, the electric screwing device comprising a rotating tool. Hexagonal bit (22) is rotatably held. The device (1) according to the invention, in all five embodiments, likewise comprises a measuring device (23), which comprises a current measuring device and an encoder. Both the current measuring device and the encoder are integrated in the electric screwing device (21). As shown in FIGS. 6 and 7, the measuring device (23) also includes a strain gauge (24) provided outside the main body (5). 5 is not shown simply from the viewpoint of legibility. In addition, the device (1) according to the invention is connected in all five embodiments to an evaluation and control device (25) connected to the measuring device (23) and to the evaluation and control device (25). A signaling device (26) in the form of two LED lamps.

  In the following, the technical differences of five embodiments of the device (1) according to the invention for operating the hydraulic expansion chuck (3) will be described.

  In the first embodiment in FIG. 1, the holding device (2) for the hydraulic expansion chuck (3) is a stationary holding part and is fixed to the base plate (27) of the device (1). In this embodiment, the device (1) also comprises an adjusting device (28), which comprises a holding part (29) for an electric screw tightening device (21) and a uniaxial movement mechanism (30). ). The adjusting device (28) is likewise fixed to the base plate (27).

  In the second embodiment in FIG. 2, the holding device (2) for the hydraulic expansion chuck (3) comprises a displaceable shaft (31) and two rotary joints (32), thus It has two translational degrees of freedom and two rotational degrees of freedom, so that the direction and position of the hydraulic expansion chuck (3) can be adjusted. The holding device (2) is fixed to the base plate (27) of the device (1). As in the first embodiment, also in the second embodiment, the device (1) comprises an adjusting device (28), the adjusting device being a holding part for an electric screw tightening device (21). (29) and a uniaxial movement mechanism (30). The adjusting device (28) is likewise fixed to the base plate.

  In the third embodiment in FIG. 3, the holding device (2) for the hydraulic expansion chuck (3) is a stationary holding part, which is fixed to the base plate (27) of the device (1). is there. Here, the device (1) also comprises an adjusting device (28). However, unlike the first and second embodiments, the adjustment device (28) is not a uniaxial motion mechanism but an industrial robot.

  In the fourth embodiment in FIG. 4, the holding device (2) for the hydraulic expansion chuck (3) is a stationary holding part and is fixed to the base plate (33) of the gripping robot device (34). Things. The main unit (35) of the gripping robot device (34) is connected to the base plate (33) and extends vertically, and the gripping arm (36) protrudes. This gripping arm (36) is for delivering and removing the operated hydraulic expansion chuck. As in the first and second embodiments, also in the fourth embodiment, the device (1) is provided with an adjusting device (28), which is an electric screw tightening device (21). And a uniaxial motion mechanism (30). The adjusting device (28) is connected to the base plate (33) of the gripping robot device (34).

  In the fifth embodiment in FIG. 5, the holding device (2) for the hydraulic expansion chuck (3) is a stationary holding part and has a base plate (37). The base plate (37) includes a through hole (38) for fixing the holding device (2) to the table. Unlike the four embodiments described above, the device (1) according to the fifth embodiment does not include an adjusting device (28). Instead, electric screwdrivers are formed as portable, battery-operated screwdrivers that can be charged via a charging device.

  During operation of the device (1) for operating the hydraulic expansion chuck, the electric screwing device (21) is operated manually in the fifth embodiment or in the first four embodiments by the adjusting device (21). 28) is automatically oriented relative to the hydraulic expansion chuck (3) and engages the clamping bolt (9). In FIGS. 6 and 8, the direction in which the orientation is made is indicated by arrows. The clamp bolt (9) is screwed into the screw hole (8) using the electric screw tightening device (21) until the clamp bolt (9) contacts the stopper (10). The torque applied to the hydraulic expansion chuck (3) during the screwing of the clamping bolt (9) is supported by the holding device (2). The clamp bolt (9) is adjusted in the axial direction when screwed into the screw hole (8). Since the clamp bolt (9) is connected to the clamp piston (12), the axial adjustment of the clamp bolt (9) also results in the axial adjustment of the clamp piston (12) including the sealing element (13). Thereby, the hydraulic medium in the pressure chamber system is pressed in the direction of the pressure chamber (15), whereby the wall (18) is elastically deformed or hydraulically expanded. Due to the expansion of the wall (18), first the chuck gap between the wall (18) and the tool (20) to be clamped is compensated and then the tool (20) to be clamped is fixed. The wall (18) is pressed, which creates a frictional connection between the hydraulic expansion chuck (3) and the tool (20).

  During the screwing of the clamping bolt (9), the strain gauge (24) of the measuring device (23) causes the deformation, in particular the expansion, of the body (5) to change the hydraulic medium pressure minus the pressure of the hydraulic medium as the indicated value. And measure as a complementary amount. In addition, the measuring device (23) uses a current measuring device to preset the motor current of the electric screw tightening device (21) at a constant motor speed, and thus the torque of the clamp bolt indirectly. Hydraulic medium pressure at uniform intervals-measured as another complementary quantity to the pressure of the hydraulic medium as an indicated value. Further, the measuring device (23) uses the encoder to change the rotation angle of the clamp bolt (9) in the screw hole (8) as the clamp bolt stroke at the uniform measurement interval set in advance-the display value. It is measured as a complementary amount to the axial stroke position of the bolt (9). In this embodiment, the measurement of the rotation angle is initiated by the occurrence of a trigger event, ie, the occurrence of contact of the clamping surface (19) with the tool (20). Of course, the measurement can be started at another time or taken from scratch. The measurement interval between two directly measured torques corresponds to the measurement interval between two directly measured rotation angles. Therefore, after the clamp bolt (9) is rotated by a predetermined angle range, the torque at the clamp bolt (9) is measured.

  Then, the evaluation / control device (25) determines whether the torque measured or the deformation measured when the clamp bolt (9) is screwed is changed into the characteristic torque or characteristic deformation of the hydraulic expansion chuck (3) used. Is checked within a predetermined range, and if the check result is positive, the clamp state assigned to the characteristic torque or characteristic deformation is inferred. At this time, on the one hand, the characteristic torque / deformation is the characteristic torque / deformation at the time of contact of the clamping surface (19) with the tool (20), and the assigned clamping state is the clamping surface (19). Contact between the tool and the tool (20) or the attainment of a minimum clamping force. On the other hand, the characteristic torque / deformation is the characteristic torque / deformation at the time of the abutment of the clamp bolt (9) on the stopper (10), and the assigned clamping state is a predefined target clamping force. Is reached.

  In addition, the evaluation and control device (25) calculates the gradient of the measured torque. This gradient is formed by the amount of difference between each two torques measured directly in succession as a dividend and the measurement interval between the two torques considered as a divisor. Then, the evaluation / control device (25) specifies a gradient change between each of the two calculated gradients calculated based on the three torques measured directly and continuously. For this purpose, the two calculated slopes are divided. Following this, it is checked whether the predetermined gradient change is outside a predefined range, and thus whether there is a clear gradient change. Obvious gradient changes exist, for example, when the gradients differ from each other multiple times. A possible cause of the identified apparent gradient change is identified, and a clamp condition is inferred based on the identified cause.

  The cause of the presence of the apparent gradient change is identified by comparing the torque measured at the time of the apparent gradient change to at least one known characteristic target value for the torque for the hydraulic expansion chuck used. You. At this time, the target value for the torque is the torque when the clamp surface (19) comes into contact with the tool (20) and / or when the clamp bolt (9) comes into contact with the stopper (10). For further protection, the measured rotation angles are taken into account. The rotation angle measured at the time of the apparent gradient change is compared with at least one known, desired value for the rotation angle characteristic of the hydraulic expansion chuck (3). If it occurs that the measured rotation angle is significantly smaller than the target value, then a cause for the presence of a clear gradient change is, for example, a hydraulic expansion chuck (3) such as clamping bolt (9) catching. The fault is identified.

  When the contact of the clamp (19) with the tool (20) is estimated as the cause of the existence of the apparent gradient change, the reaching of the minimum clamping force is estimated as the clamp state based on the cause. On the other hand, when the contact of the clamp bolt (9) with the stopper (10) is estimated as a cause of the existence of the apparent gradient change, the torque measured at the time of the apparent gradient change is determined by the hydraulic type. A comparison is made with a known value for the torque at the time of contact of the clamp bolt (9) with the stopper (10), which is characteristic of the extension chuck. When the coincidence of the two torques to be compared with each other is confirmed within a predetermined range, it is estimated based on the confirmation that the target clamping force in the clamp state has been reached.

  Then, the specified clamp state is displayed to the user by turning on the corresponding LED lamp (26).

  FIG. 9 shows qualitatively two typical measurement curves which can be obtained in the operating method described above during the screwing of the clamping bolt (9). Specifically, the measured torque is entered for the measured rotation angle.

  The measurement curve indicated by II shows a typical torque curve for the case where the tool (20) is in the tool housing (17) of the hydraulic expansion chuck (3). The measurement curve has three parts, each with a different slope. In the first part (1), the torque is approximately linearly proportional to the expansion rate of the wall (18). In this portion, the wall portion (18) expands due to the screwing of the clamp bolt (9). As soon as the clamping surface (19) comes into contact with the shank of the tool (20), which corresponds at point A of the measurement curve II, a positive pressure jump of the hydraulic medium in the pressure chamber system of the hydraulic expansion chuck (3), ie This leads to a sharp rise in pressure, which is manifested by a clear rise in the slope of the measurement curve. Thus, at point A of the measurement curve II, the first part transitions to a second part having a significantly greater slope than the first part. In the second part, the change in the expansion rate is no longer made. Rather, a further screwing of the clamping bolt (9) in the direction of the stopper (10) leads to an increase in the pressure of the hydraulic medium. This is, inter alia, related to the fact that the hydraulic medium, in particular the hydraulic oil, is at least easily compressible at the high pressures which are occurring in the hydraulic expansion chuck. At this time, the torque in the second portion is linearly proportional to the pressure of the hydraulic medium. As soon as the clamping bolt (9) reaches the stop (10), a second positive pressure jump is reached, which is acted upon by the stop (10) due to a new apparent increase in the slope of the measurement curve II. Surface based on additional axial force. Thus, point B of measurement curve II temporarily indicates a second pressure jump. Here, the second part transitions to a third part, which has a significantly greater gradient than the second part. The fact that the clamping bolt (9) can rotate slightly more in the third part is, inter alia, that the components of the hydraulic expansion chuck (3) are elastically slightly compressed, for example as a stopper (10). Related to

  The measurement curve indicated by I shows a typical torque curve for the case where the tool (20) is not in the tool housing (17) of the hydraulic expansion chuck (3). The measurement curve has only a pressure jump at point B, which is caused by the clamp bolt (9) reaching the stop (10). There is no further pressure jump at point A since the tool (20) is not in the tool receptacle (17). This is because the clamping surface (19) does not come into contact with the tool (20).

REFERENCE SIGNS LIST 1 Device for operating hydraulic expansion chuck 2 Holding device 3 Hydraulic expansion chuck 4 Main device 5 Main unit 6 Machine interface 7 Clamping range 8 Screw hole 9 Clamp bolt 10 Stopper 11 Cylindrical hole 12 Clamp piston 13 Seal element 14 Expansion bush 15 Pressure chamber 16 Front end face of main body 17 Tool housing 18 Wall 19 Clamping surface 20 Tool 21 Electrical screw tightening device 22 Hexagonal bit 23 Measuring device 24 Strain gauge 25 Evaluation / control device 26 Signaling device 27 Base plate 28 Adjusting device 29 Holder for electric screw tightening device 30 Uniaxial motion mechanism 31 Displaceable shaft 32 Rotary joint 33 Base plate 34 Grasping arm robot device 35 Main unit 36 Grasping arm 37 Base plate 38 Through hole 39 Collector

Claims (75)

A method for operating a hydraulic extension clamping device (3), in particular a hydraulic extension chuck or a hydraulic extension mandrel, said hydraulic extension clamping device (3) having a body device (4). The body device (4) is formed with a pressure chamber system filled with a hydraulic medium, the pressure chamber system including a pressure chamber (15) and a screw hole (8), wherein the pressure chamber (15) Has a wall (18) defining a clamping surface (19) on the opposite side of the pressure chamber (15), the screw hole (8) being drilled from the outside into the main unit (4), It is connected to the pressure chamber (15) through a connection passage, a clamp bolt (9) is screwed into the screw hole (8), and the clamp bolt is screwed into the screw hole (8). Tool (20) or workpiece The hydraulic medium is pressed in the direction of the pressure chamber (15) to fix the ramp, the wall (18) is axially adjusted to be elastically deformed, and the clamp bolt (9) is The torque, which is rotated using the rotary tool (22) and is brought to the hydraulic extension clamping device (3), is supported in the stationary holding part (2), in particular by the fixing of the hydraulic extension clamping device (3). ,
The following steps:
a) measuring the hydraulic medium pressure-indicated value with a measuring device (23) at a preset uniform measuring interval and / or continuously during the rotation of said clamp bolt (9);
b) using an evaluation and control device (25) to evaluate the measured hydraulic medium pressure-display value to specify a clamp state of the hydraulic expansion clamp device (3);
c) signaling the determined clamping state of the hydraulic expansion clamping device (3) to a user using a signaling device (26).   The rotating tool (22) is automatically oriented relative to the hydraulic extension clamping device (3) and is automatically engaged with the clamping bolt (9). 2. The method according to 1.   The clamping bolt (9) can be automatically turned by means of a screwing device (21) holding the rotating tool (22), in particular an electric screwing device, or by means of the rotating tool (22), in particular a screwdriver. Method according to claim 1 or 2, characterized in that it is manually rotated using (1).   In step a), the value of the pressure of the hydraulic medium during the screwing of the clamp bolt (9) is measured as a hydraulic medium pressure-indicated value via a pressure sensor in the pressure chamber system. The method according to claim 1.   In step a), the value of the pressure of the hydraulic medium during the screwing of the clamp bolt (9) is measured as the hydraulic medium pressure minus the indicated value via the pressure sensor in the clamp bolt (9). The method according to any one of claims 1 to 4, wherein   The axial adjustment of the clamp bolt (9) when screwed into the screw hole (8) causes an axial adjustment of the clamp piston (12), the clamp piston being axially displaced by the screw. In the cylindrical bore (11) of the pressure chamber system adjacent to the bore (8) and in contact with or connected to the clamp bolt (9), in step a) the clamp bolt The pressure value of the hydraulic medium is measured via a pressure sensor as the hydraulic medium pressure at the clamp piston (12) during the screwing in (9). The method according to any one of claims 1 to 4.   2. The method according to claim 1, wherein in step a) the value of the amount complementary to the pressure of the hydraulic medium is measured as the hydraulic medium pressure during the screwing of the clamp bolt (9) minus the indicated value. 7. The method according to any one of 6.   The deformation, in particular the expansion and / or the extension, of the body device (4) as a complementary quantity to the pressure of the hydraulic medium is measured using a strain gauge (24) as the hydraulic medium pressure-display value. The method according to claim 7, characterized in that:   Method according to claim 7 or 8, characterized in that the torque at the clamp bolt (9) as a complementary quantity to the pressure of the hydraulic medium is measured as hydraulic medium pressure-indicated value.   Method according to claim 9, characterized in that the measurement of the torque at the clamping bolt (9) is made through the measurement of the torsion of the torsion shaft using a strain gauge provided on the torsion shaft.   The clamp bolt (9) is rotated using an electric screw tightening device (21) holding the rotating tool (22), and the measurement of the torque of the clamp bolt (9) is performed at a constant motor rotation speed. Method according to claim 9 or 10, characterized in that the determination is made via measurement of the motor current of the motor of the electric screw-fastening device (21) in.   The clamp bolt stroke-the indicated value is preset during the screwing of said clamp bolt (9), in particular when a predefined trigger event has occurred or a predefined trigger value has been measured. The method according to any of the preceding claims, characterized in that the measurements are taken at equal measuring intervals and / or continuously.   The trigger event may be caused by contact of the clamping surface (19) with a tool (20) or workpiece to be clamped and / or with a stopper (10) that limits the axial adjustment of the clamping bolt (9). The abutment of the clamp bolt (9) and / or the trigger value may be a hydraulic medium pressure value or a characteristic of the hydraulic expansion clamp device (3) used in a predetermined trigger event. 13. The method of claim 12, wherein the value of the quantity is complementary to   14. The method according to claim 12, wherein the value of the axial stroke position of the clamp bolt (9) in the screw hole (8) is measured as clamp bolt stroke-display value.   13. A method according to claim 12, wherein a value of an amount complementary to an axial stroke position of said clamp bolt in said screw hole is measured as clamp bolt stroke-display value. 15. The method according to any one of 14.   The rotation angle of the clamp bolt (9) as a complementary amount to the axial stroke position of the clamp bolt (9) in the screw hole (8) is preferably determined using an encoder and / or a Hall sensor. The clamp bolt stroke is measured directly at the clamp bolt (9) or at the rotary tool (22) or in the screw tightening device (21) holding the rotary tool (22) as a clamp bolt stroke-indicated value. The method of claim 15, wherein:   17. The method according to claim 16, wherein the returned stroke of the clamp bolt (9) is calculated using the measured rotation angle and the known pitch of the screw of the clamp bolt (9). .   The measuring interval between two directly measured hydraulic medium pressures-indicating values is the measuring interval between two directly measured clamping bolt strokes-indicating values, in particular the clamping bolt (9) 18. The method according to any one of claims 12 to 17, wherein the method corresponds to a preset stroke step, angle step, or time step when the screw-in speed is constant. In step b), the following partial steps:
b1) The hydraulic medium pressure-indicated value measured when the clamp bolt (9) is screwed in is within a predefined range for the hydraulic medium pressure-indicated value characteristic of the type of hydraulic extension chuck used. Checking whether or not
b2) if the check in step b1) is a positive result, estimating the clamping state of the hydraulic extension clamping device (3) assigned to the characteristic hydraulic medium pressure-display value; The method according to claim 1, wherein the method is performed.   The characteristic hydraulic medium pressure-display value is a characteristic hydraulic medium pressure-display value at the time of contact of the clamping surface (19) with a tool (20) or a workpiece to be clamped, and The clamped state is a contact between the clamping surface (19) and the tool (20) or the work piece, and / or the characteristic hydraulic medium-indicated value is the clamping bolt (9) The characteristic hydraulic medium pressure-display value when the clamp bolt (9) comes into contact with the stopper (10) that limits the axial adjustment of 20. Method according to claim 19, characterized in that a predefined target clamping force of the extension clamping device (3) is reached. In step b), the following partial steps:
b3) a step of calculating the gradient of the hydraulic medium pressure-display value measured at a predetermined uniform measurement interval during the screwing of the clamp bolt (9) in the step a), wherein the gradient is calculated continuously with each other. Forming a gradient based on the measured difference between each two hydraulic medium pressure-display values or its value as dividend and the measured interval between the two hydraulic medium pressure-display values considered as divisor;
b4) identifying a gradient change between each two computed gradients;
b5) checking whether the specified gradient change is outside a predefined range, and thus whether there is an obvious gradient change;
b6) identifying possible causes for said apparent gradient change, especially by taking into account further measured values and / or target values;
b7) estimating a clamping state of the hydraulic extension clamping device (3) based on the specified cause. Method.   22. The method according to claim 21, wherein the gradient change between the two gradients calculated from the three hydraulic medium pressures-display values measured directly directly in step b3) is determined in step b4). .   23. The method according to claim 21 or 22, wherein the gradient change is determined in step b4) by subtracting or dividing the two gradients calculated in step b3).   Prior to calculating the gradient in step b3), the scale in which the measured hydraulic medium pressure-indicated value in step a) has a multiple of the measurement interval between two directly measured hydraulic medium pressure-indicated values And the resulting measurement curve is smoothed, in particular by the calculation of a moving average, and / or at least one particularly linear curve fit in said measurement curve is performed. 24. The method according to any one of claims 21 to 23.   19. In addition to the hydraulic medium pressure-indicated value measured in step a), the clamping bolt stroke-indicated value according to any one of claims 12 to 18 is measured and two directly measured oil pressures are measured directly and continuously. 25. The method according to claim 21, wherein the measuring interval between the medium pressure and the indicated value corresponds to the measuring interval between two directly measured clamp bolt strokes and the indicated value. .   In step b6), the measured clamp bolt stroke-display value at the time of the apparent gradient change is at least the known clamp bolt stroke-display value characteristic for the type of hydraulic extension clamping device used. 26. The method according to claim 25, wherein a cause for the presence of an apparent gradient change is identified by comparison with a single target value.   The clamp bolt stroke—the target value for the indicated value is determined when the clamp surface (19) contacts the tool (20) or workpiece to be clamped and / or the axis of the clamp bolt (9). Method according to claim 26, characterized in that the clamping bolt stroke at the time of contact of the clamping bolt (9) at the stopper (10) limiting the directional displacement is the displayed value.   12. The torque of the clamp bolt (9) as a complementary amount to the pressure of the hydraulic medium when the clamp bolt (9) is screwed in, as the hydraulic medium pressure-display value, in particular, any of claims 9 to 11. The clamp bolt stroke measured in step b6) and measured in step b6) based on a comparison between the measured clamp bolt stroke and the target value of the measured clamp bolt stroke at the time of the apparent gradient change. When the indicated value is outside the range for the target value and is therefore much smaller than the target value, the hydraulic expansion clamping device (3) as a cause for the presence of a clear gradient change; 28. The method of claim 26 or claim 27, wherein a fault is identified.   Method according to claim 28, characterized in that the failure of the hydraulic expansion clamping device (3) is identified as a catch of the clamping bolt (9) in the screw hole (8).   In step b6), the measured hydraulic medium pressure-indicator value at the time of the apparent gradient change is at least the known hydraulic medium pressure-indicator value characteristic of the type of hydraulic expansion clamp used. 30. A method as claimed in any one of claims 21 to 29, wherein a cause for the presence of an apparent gradient change is determined by comparison with one target value.   The target value for the hydraulic medium pressure-indicated value is determined when the clamping surface (19) contacts the tool (20) or workpiece to be clamped and / or the axis of the clamping bolt (9). 31. Method according to claim 30, characterized in that the hydraulic medium pressure at the time of contact of the clamp bolt (9) at the stopper (10) limiting the directional displacement is the indicated value.   In step b6), the contact of the clamping surface (19) with the tool (20) or workpiece to be clamped was presumed to be the cause of the apparent gradient change and was identified in step b7). 32. The method according to any one of claims 21 to 31, wherein based on the cause, reaching the minimum clamping force is estimated as a clamping state. The following further steps:
Inferring the contact of said clamp bolt (9) with a stopper (10) limiting the axial adjustment of said clamp bolt (9) in step b6) as a cause of the apparent gradient change; ,
The pressure value of the hydraulic medium at the time of the apparent gradient change, the pressure value at the time of contact of the clamp bolt (9) at the stopper which limits the axial adjustment of the clamp bolt (9); Comparing to a known target value characteristic of the type of hydraulic expansion clamping device used;
-Confirming that the two hydraulic medium pressures to be compared with each other-the indicated values match within a predefined range;
Estimating the attainment of the target clamping force in step b7) as a clamped state based on a prior confirmation. 32. The method according to any one of claims 21 to 31.   In step b), when it is confirmed at the time of evaluating the measured hydraulic medium pressure-display value that a predetermined OFF condition is satisfied, the clamp bolt (22) using the rotary tool (22) is used. The method according to any one of claims 1 to 33, wherein the screwing in (9) is terminated.   The predetermined off condition is determined by the type of the hydraulic extension clamping device used when the clamping bolt (9) comes into contact with a stopper (10) that limits the axial adjustment of the clamping bolt (9). 35. The method according to claim 34, characterized in that it is a known hydraulic medium pressure-display value which needs to be achieved within a characteristic, predefined range.   36. The method according to claim 1, wherein the clamping state specified in step c) is signaled to the user by means of an indication via an optical signal, an acoustic signal or a vibration signal. The described method. A hydraulic extension clamping device (1), in particular a device for operating a hydraulic extension chuck or a hydraulic extension mandrel, said hydraulic extension clamping device (1) having a body device (4); The body device (4) is formed with a pressure chamber system filled with a hydraulic medium, said pressure chamber system including a pressure chamber (15) and a screw hole (8), wherein the pressure chamber (15) is On the opposite side from the pressure chamber (15), it has a wall (18) defining a clamping surface (19), the screw hole (8) being drilled from the outside into the main unit (4), Is connected to the pressure chamber (15) via a screw hole, a clamp bolt (9) is screwed into the screw hole (8), and the clamp bolt is screwed into the screw hole (8), whereby a tool ( 20) Or clamp the workpiece So as to fix the hydraulic medium is pressed in the direction of the pressure chamber (15), said wall portion (18) is adjusted in the axial direction so as to be elastically deformed,
The device (1)
-A device comprising a holding device (2), in particular a stationary holding portion, configured to support a torque applied to the hydraulic expansion clamping device (3) when the clamping bolt (9) rotates.
A measuring device (23) configured to measure the hydraulic medium pressure-indicated value at predetermined equal measuring intervals during rotation of said clamp bolt (9) and / or continuously;
A hydraulic medium pressure measured by said measuring device (23)-an evaluation and control device (25) formed to evaluate the indicated value and to specify the clamping state of said hydraulic extension clamping device (3);
A signaling device (26) configured to signal the user of the clamping state of the hydraulic extension clamping device (3) identified by the evaluation and control device (25). apparatus.   Apparatus (1) according to claim 37, comprising a rotating tool (22) configured to rotate the clamp bolt (9).   It comprises a screw tightening device (21), in particular an electric screw tightening device, which holds the rotary tool (22) for automatically rotating the clamp bolt (9). Device (1) according to claim 38, characterized in that:   An adjusting device (28) having a holding portion (29) for the rotating tool (22) or a screw tightening device (21) holding the rotating tool (22) is provided. 40. Device (1) according to claim 38 or 39, characterized in that it is automatically oriented relative to the hydraulic expansion clamping device (3) and is automatically engaged with the clamping bolt (9). ).   The adjusting device (28) has a one-axis, two-axis, three-axis or five-axis movement mechanism, and is in particular a combination of an industrial robot such as a folding arm robot or a linear module and a rotation axis. Device (1) according to claim 40, wherein:   The holding device (2) is provided with a support surface corresponding to the support surface of the hydraulic expansion clamp device (3), and / or the holding device (2) is a vise. Apparatus (1) according to any one of claims 37 to 41.   The measuring device (23) includes a pressure sensor, which is configured to measure the pressure of the hydraulic medium as the hydraulic medium pressure-indicated value in the hydraulic chamber system during the screwing of the clamp bolt. 43. Apparatus (1) according to any one of claims 37 to 42, characterized in that:   The measuring device (23) includes a pressure sensor, which measures the pressure of the hydraulic medium during the screwing of the clamp bolt (9) as the hydraulic medium pressure at the clamp bolt (9)-the indicated value. Device (1) according to any one of claims 37 to 43, characterized in that it is configured to measure.   The axial adjustment of the clamp bolt (9) when screwed into the screw hole (8) causes an axial adjustment of the clamp piston (12), the clamp piston being axially displaced by the screw. In the cylindrical bore (11) of the pressure chamber system adjacent to the bore (8) and in contact with or connected to the clamp bolt (9), the measuring device (23) A pressure sensor, which is configured to measure the pressure of the hydraulic medium as the hydraulic medium pressure at the clamp piston (12) during the screwing of the clamp bolt (9) minus the indicated value. Device (1) according to any one of claims 37 to 43, characterized in that it is a device.   The measuring device (23) is configured to measure a value of an amount complementary to the pressure of the hydraulic medium as the hydraulic medium pressure-display value during the screwing of the clamp bolt (9). Apparatus (1) according to any one of claims 37 to 45, characterized in that:   The measuring device (23) includes a strain gauge (24) in the main body device (4), and the strain gauge (24) has a main body ( 47. Device (1) according to claim 46, characterized in that it is configured to measure the deformation, in particular expansion and / or extension, of 4) as hydraulic medium pressure-indicated value.   The measuring device (23) is configured such that the torque as a complementary amount to the pressure of the hydraulic medium is measured as the hydraulic medium pressure during the screwing of the clamp bolt (9)-the indicated value. Apparatus (1) according to claim 46 or 47, characterized in that:   The measuring device (23) includes a strain gauge, and the strain gauge is provided on a torsion shaft, and the strain gauge measures a torsion of the torsion shaft, and based on the measured torsion of the clamp bolt (9). 49. Apparatus according to claim 48, characterized in that the torque and the pressure of the hydraulic medium can be calculated therefrom.   An electric screw tightening device (21) having a motor is provided, the electric screw tightening device (21) holds the rotating tool (22), and the measuring device (23) is provided with an electric current A current measuring device for measuring a motor current of the electric screw tightening device (21) at a constant motor speed, and based on the measured torque, a torque at the clamp bolt (9); 50. Apparatus (1) according to claim 48 or 49, characterized in that it is further arranged to be able to calculate the pressure of the hydraulic medium on the basis of:   The measuring device (23) starts the clamp bolt stroke-indicated value, in particular by the occurrence of a predefined trigger event or measuring a predefined trigger value, to determine the clamp bolt stroke (9). The measuring interval between two hydraulic medium pressures-reading values, which is designed to be measured at a predetermined uniform measuring interval during the screw-in and / or continuously and is measured directly directly Device (1) according to one of the claims 37 to 50, characterized in that in particular, corresponds to the measuring interval between two clamp bolt strokes which are measured directly consecutively-the indicated value. .   The trigger event may be caused by contact of the clamping surface (19) with a tool (20) or workpiece to be clamped and / or at a stop (10) which limits the axial adjustment of the clamping bolt (9). The abutment of a clamping bolt (9) and / or the trigger value may or may not be the value of the hydraulic medium pressure characteristic for the hydraulic extension clamping device (3) used in a given trigger event. Device (1) according to claim 51, characterized in that the values are complementary values.   The measuring device (23) is formed to measure a value of an axial stroke position of the clamp bolt (9) in the screw hole (8) as a clamp bolt stroke-display value. Device (1) according to claim 51 or 52.   The measuring device (23) is configured to measure a value of an amount complementary to an axial stroke position of the clamp bolt (9) in the screw hole (8) as a clamp bolt stroke-display value. Apparatus (1) according to any one of claims 51 to 53, characterized in that:   The measuring device (23) clamps a rotation angle of the clamp bolt (9) as an amount complementary to an axial stroke position of the clamp bolt (9) in the screw hole (8). Bolt stroke-formed as a measured value directly at the clamp bolt (9) or at the rotary tool (22) or at a screw tightening device (21) where the rotary tool (22) is held. Device (1) according to claim 54, characterized in that the device (1) is   56. The device (1) according to claim 55, wherein the measuring device (23) comprises an encoder and / or a Hall sensor, whereby the rotation angle of the clamp bolt (9) is measured.   The evaluation and control device (25) is configured to calculate the returned stroke of the clamp bolt (9) using the measured rotation angle and the known pitch of the screw of the clamp bolt (9). Device (1) according to claim 55 or 56, characterized in that:   The evaluation / control device (25) is configured to determine whether the hydraulic medium pressure-display value measured when the clamp bolt (9) is screwed in is a hydraulic medium pressure-display value characteristic of the type of the hydraulic expansion chuck used. Checking if it is within a predefined range, and if the check is positive, clamp the hydraulic extension clamping device (3) assigned to the characteristic hydraulic medium pressure-display value The device (1) according to any one of claims 37 to 57, characterized in that the device (1) is configured to infer a state.   The characteristic hydraulic medium pressure-display value is a characteristic hydraulic medium pressure-display value at the time of contact of the clamping surface (19) with a tool (20) or a workpiece to be clamped, and The clamped state is a contact between the clamping surface (19) and the tool (20) or the work piece, and / or the characteristic hydraulic medium-indicated value is the clamping bolt (9) The characteristic hydraulic medium pressure-display value when the clamp bolt (9) comes into contact with the stopper (10) that limits the axial adjustment of Device (1) according to claim 58, characterized in that the predefined clamping force of the expansion clamping device (3) is reached. The evaluation / control device (25) includes:
Calculating the gradient of the hydraulic medium pressure-indicated value measured by the measuring device (23) at predetermined equal measuring intervals during the screwing of the clamp bolt (9) and measuring them continuously with each other; A gradient is formed based on the difference between the two hydraulic medium pressure-display values or the value as the dividend and the measured interval between the two hydraulic medium pressure-display values to be considered as the divisor, respectively;
-To specify the gradient change between each two calculated gradients,
-To check whether the specified slope change is outside the predefined range, and thus whether there is an obvious slope change,
To identify possible causes for said apparent gradient change, in particular by taking into account further measured values and / or target values; and based on said identified causes, said hydraulic expansion clamp The device (1) according to any one of claims 37 to 59, characterized in that the device (1) is configured to estimate the clamping state of the device (3).   The evaluation and control device (25) is configured to identify a gradient change between two gradients calculated based on three directly-measured hydraulic medium pressure-display values. Apparatus (1) according to claim 60, wherein   61. The device according to claim 60, wherein the evaluation and control device is configured to determine the gradient change by subtracting or dividing the two computed gradients. The device (1) according to 61.   Before the calculation of the gradient, the evaluation / control device (25) compares the hydraulic medium pressure-display value measured by the measuring device (23) with the two hydraulic medium pressures directly and continuously measured. Plotting against a scale having a multiple of the measurement interval between the indicated values, the resulting measurement curve is smoothed, in particular by the calculation of a moving average, and / or at least one particularly linear curve in said measurement curve 63. Apparatus (1) according to any one of claims 60 to 62, characterized in that it is configured to perform a simple curve fitting.   58. The measuring device (23) according to any one of claims 51 to 57, wherein the measuring device (23) is configured to measure a clamp bolt stroke-two indicated hydraulic fluid pressures which are measured directly and continuously. 64. Apparatus (1) according to any one of claims 60 to 63, wherein the measuring interval between the indicated values corresponds to the measuring interval between two directly measured clamp bolt strokes-the indicated values. .   The evaluation and control device (25) compares the measured clamp bolt stroke at the time of the apparent gradient change-the indicated value with the known clamp bolt stroke-characteristic for the type of hydraulic extension clamping device used. 65. The device (1) according to claim 64, characterized in that a comparison with at least one target value for the indicated value determines the cause for the presence of a clear gradient change.   The clamp bolt stroke—the target value for the indicated value is determined when the clamp surface (19) contacts the tool (20) or workpiece to be clamped and / or the axis of the clamp bolt (9). Device (1) according to claim 65, characterized in that it is the clamp bolt stroke when the clamp bolt (9) abuts on the stopper (10) limiting the directional displacement-the indicated value.   The measuring device (23) measures, when the clamp bolt (9) is screwed in, the torque of the clamp bolt (9) as a complementary amount to the pressure of the hydraulic medium as a hydraulic medium pressure-display value. The evaluation and control device (25) compares the clamp bolt stroke-display value measured at the time of the apparent gradient change with the target value of the clamp bolt stroke-display value. The measured clamp bolt stroke-when the measured value is outside the range for the target value and therefore much smaller than the target value, as a cause for the presence of an apparent gradient change 67. Apparatus according to claim 65 or 66, characterized in that a failure of the hydraulic extension clamping device (3) is determined. (1).   68. The device (1) according to claim 67, wherein the failure of the hydraulic extension clamping device (3) is a catch of the clamping bolt (9) in the screw hole (8).   The evaluation and control device (25) comprises a hydraulic medium pressure-measurement value measured at the time of an apparent gradient change and a known hydraulic medium pressure-characteristic characteristic of the type of hydraulic extension clamping device used. 69. The method according to claim 60, further comprising the step of: comparing the display value with at least one target value to determine a cause of the presence of the apparent gradient change. Device (1).   The target value for the hydraulic medium pressure-indicated value is determined when the clamping surface (19) contacts the tool (20) or workpiece to be clamped and / or the axis of the clamping bolt (9). 70. Device (1) according to claim 69, characterized in that it is the hydraulic medium pressure when the clamp bolt (9) abuts on the stopper (10) limiting the displacement in the direction-the indicated value.   The evaluation and control device (25) infers the contact of the clamping surface (19) with the tool (20) or the workpiece to be clamped as a cause of the presence of a clear gradient change and based on the cause. Apparatus (1) according to any of claims 60 to 70, characterized in that it is configured to assume that the minimum clamping force has been reached as a clamped state. The evaluation / control device (25) includes:
Guessing the contact of the clamp bolt (9) with a stopper (10) limiting the axial adjustment of the clamp bolt (9) as the cause of the apparent gradient change;
-The hydraulic medium pressure measured by the measuring device (23) at the time of the apparent gradient change-the value indicated by the clamp bolt (9) at the stopper (10) which limits the axial adjustment of the clamp bolt (9). The hydraulic medium pressure at the time of abutment-for the indicated value, compared with a known target value characteristic of the type of hydraulic expansion clamp device used,
-Confirming that the two hydraulic medium pressures to be compared with each other-the indicated values are consistent within a predefined range;
72. Apparatus (1) according to any of claims 60 to 71, characterized in that, based on said confirmation, the arrival of the target clamping force is estimated as a clamping state.   The evaluation / control device (25) is configured to check whether a predetermined OFF condition is satisfied, and to terminate the screwing of the clamp bolt (9) if the check result is positive. Device (1) according to any one of claims 37 to 72, characterized in that:   The predetermined off condition is determined by the type of the hydraulic extension clamping device used when the clamping bolt (9) comes into contact with a stopper (10) that limits the axial adjustment of the clamping bolt (9). 74. Device (1) according to claim 73, characterized in that it is a characteristic known hydraulic medium pressure-display value.   75. Apparatus (1) according to any of the claims 37 to 74, wherein said signaling device (26) comprises a lamp, a speaker, a display and / or a vibration device.